Fig. 5. Functional mapping of the AIF domains regulating SG formation. (A) Repression of SG formation by retransfection with mouse AIF. HeLa cells manipulated to downregulate endogenous (human) AIF (siRNA-AIF) were re-transfected with V5-tagged mouse AIF, either full length (AIF WT) or deleted in its N-terminus (AIF1-100) which contains the mitochondrial localization sequence, together with the SG inducer G3BP-GFP. Twenty-four hours after transfection, the cells were stained with an antibody recognizing the V5 epitope. Note that no SGs are formed upon transfection with wild-type AIF, which accumulates in mitochondria (middle panel), whereas AIF1-100 (which distributes in a diffuse fashion) does not suppress SG formation. (B) Deletion mutations that affect different regions of the AIF molecule. (C,D) Effect of different mouse AIF deletion constructs on SG formation elicited with G3BP (C, done as in A) or HAsO₄ (D, incubation for 3 hours with 1 mM HAsO₄, 24 hours after re-transfection of AIF into cells). Note that the control for siRNA-AIF (targeting human AIF) used in C and D was a construct designed to downmodulate emerin.